Pox herpes

POX AND HERPESVIRUSESJaime A. Santos

Saturday, May 29, 2010

Poxviruseslargest viruses

complex symmetrydouble-stranded DNAassembled in inclusion

bodies (Guarnieri bodies)


Diseasesvariola (smallpox)

vaccinia

orf

cowpox

monkeypox

othe animal poxviruses

molluscum contagiosum


Smallpoxonly infectious disease to have been eliminated by vaccination

2 forms: variola major (high mortality), variola minor


Smallpox vaccination


Molluscum contagiosum

diagnosis: molluscum bodies

treatment: cryotherapy or electrodesication


Herpesviridae

HSV-1

HSV-2

VZV

EBV

CMV

HHV-6, 7, 8


Characteristics

large, enveloped, icosahedral

encode DNA polymerase

latency, persistence

very common causes of infection


HSV 1 and 2

HSV-1 more common in oral lesions; HSV-2 in genital lesions

majority asymptomatic; skin and mucous membrane lesions, encephalitis, keratitis

congenital infection

diagnosis: serology, culture

treatment: acyclovir and related drugs


Herpes simplex 1

and 22 different viruses related

to each otherlatency in nerve ganglia

reactivation


Varicella-zoster virus

chickenpoxHerpes zoster (reactivation)

congenital varicella


Varicella (chickenpox)

self-limiting; incubation 2 weeks

milder in children

severe in neonates whoe mothers had chickenpox <5 days prior to delivery, in adults and in immunocompromised

diagnosis often clinical but can be cultured

treatment: acyclovir


Epstein-Barr virus

infects B lymphocytes - receptor is complement receptor on B cell

B cell infection leads to immortalization and polyclonal B cell stimulation

transmitted thru saliva

causes infectious mononucleosis

possibility of inducing transformation


Infectious mononucleosis

fever, lymphadenopathy, hepatosplenomegalyatypical lymphocytes (Downey cells)

heterophil antibodies


Infectious Mononucleosis

Epidemiology: different in

developing countries

Diagnosis: atypical lymphocytes

+ Monotest for heterophilantibodies

serology: + IgM anti-VCAculture: difficult


Atypical lymphocytes


EBV infection

has been associated with endemic type of Burkitt’s lymphoma and nasopharyngeal carcinoma

no practical treatment with antiviral


Cytomegalovirusvery common infection

most common cause of congenital viral infection and most common infectious cause of deafness

present in body fluids

asymptomatic; pneumonia; disseminated in immunocompromised e.g. AIDS


CMV Involvement


Congenital CMVasymptomatic to full-blown

risk in second pregnancy lower


CMV Diagnosis

cytology

serology

culture


CMV Treatment

with ganciclovir

limited to life-threatening infection and retinitis


HHV 6


Roseola infantum

common exanthem of infants

relatively benignfever for about three

days followed by rashes


HHV-8has been associated with

Kaposi’s sarcoma


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Pox herpes

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